prov: W3C Provenance for PHP

PHP implementation of the W3C Provenance Data Model (PROV-DM).

PROV-DM describes where things come from: entities (things you care about), activities (things that happen), and agents (who's responsible). Relations like wasGeneratedBy and wasAttributedTo connect them to form a provenance graph.

PROV-DM fits data lineage, audit trails, scientific-workflow provenance, attribution graphs, and any case where you need to record where information came from.

This library provides a fluent builder for assembling that graph, round-trip serializers for PROV-JSON, PROV-N, and PROV-XML (plus serialize-only PROV-JSONLD), document operations (merge, flatten, semantic equality), and a partial PROV-CONSTRAINTS validator.

Requirements

• PHP 8.4+
• ext-dom (only if you use XmlSerializer)

Installation

composer require amateescu/prov

Quick start

use Prov\Format;
use Prov\Prov;

$builder = Prov::documentBuilder();
$builder->namespace('ex', 'http://example.org/');
$builder->entity('ex:article');
$builder->activity('ex:writing', startTime: new DateTimeImmutable('2024-01-15'));
$builder->agent('ex:alice');
$builder->wasGeneratedBy(entity: 'ex:article', activity: 'ex:writing');
$builder->wasAssociatedWith(activity: 'ex:writing', agent: 'ex:alice');

$doc = $builder->build();

$json = Prov::serialize($doc, Format::Json);
echo $json;
// Other formats: Format::ProvN, Format::Xml, Format::JsonLd.

$parsed = Prov::deserialize($json, Format::Json);

The static Prov:: calls are a convenience facade. Under a dependency-injection container, construct the underlying classes directly: DocumentBuilder, the per-format serializers (Format::Json->createSerializer() / createDeserializer()), and ConstraintValidator.

Always pass relation arguments by name. PROV-DM fixes a per-relation positional order that does not follow subject-before-object. wasGeneratedBy takes (entity, activity) but used takes (activity, entity): the two sit in opposite orders even though they connect the same two records. Positional calls silently invert the relation:

// These two lines describe DIFFERENT facts, even though both identifiers are the same:
$builder->wasGeneratedBy('ex:article', 'ex:writing'); // article wasGeneratedBy writing ✓
$builder->used('ex:article', 'ex:writing');           // article used writing ✗ (reversed)

// Always use named arguments:
$builder->wasGeneratedBy(entity: 'ex:article', activity: 'ex:writing');
$builder->used(activity: 'ex:writing', entity: 'ex:article');

The optional relation identifier is the last parameter of every relation method, so a positional call binds endpoints, never the id. Pass it by name: wasGeneratedBy(entity: ..., activity: ..., identifier: 'ex:gen1').

Format support

Format	Serialize	Deserialize
PROV-JSON	yes	yes
PROV-N	yes	yes
PROV-XML	yes	yes
PROV-JSONLD	yes	no (would require an RDF-aware parser)

Output ordering

PROV serializations are unordered (a document is a set of records, namespaces a set of declarations), so ordering never affects meaning. For stable, readable output every serializer always sorts namespace declarations: the prov/xsd built-ins first, then the rest alphabetically by prefix. Records keep the order you added them by default; pass sortRecords: true to a serializer to order them into PROV-DM concept order instead (elements first, then relations in component order, each group sorted by identifier):

$json = new JsonSerializer(sortRecords: true)->serialize($doc);
// Or through the format enum, which also takes prettyPrint:
$json = Format::Json->createSerializer(sortRecords: true)->serialize($doc);

Reserved prefixes

Every serializer binds prov and xsd itself, because it writes prov:* and xsd:* terms of its own: PROV-XML on the document root, PROV-JSONLD in the @context, PROV-N through the grammar. A document that binds either prefix to another namespace keeps the namespace but not the prefix, and the names under it are written through a minted prefix, so every name still expands to the URI the model carries.

The XSD namespace has two spellings, http://www.w3.org/2001/XMLSchema (what PROV-XML binds, so that xsi:type="xsd:int" names an XML Schema type) and the same URI with a trailing # (what PROV-JSONLD and PROV-N bind). They build a different URI for every name, so a document binding xsd to the spelling a format does not use gets a minted prefix there too. Literal datatypes are the exception: an XSD datatype is written against the format's own xsd binding whichever spelling the model carries, and the two spellings compare equal.

PROV-N notes

The PROV-N parser accepts two convenience extensions beyond the published grammar, so input that parses here is not necessarily canonical PROV-N: line (//) and block (/* */) comments, and optional commas between a relation's arguments. Output always uses the canonical form.

PROV-N has no slot for an explicit identifier on specializationOf, alternateOf, hadMember, or mentionOf, and hadDictionaryMember has room for neither an identifier nor attributes. When a document carries one of these relations with an identifier (legal in PROV-JSON/PROV-XML), the PROV-N serializer drops the identifier, since the grammar cannot express it. DocumentComparator::equals() will flag the difference on a JSON-to-PROV-N-to-JSON round trip; keep such relations in PROV-JSON or PROV-XML if their identifiers matter.

The prov and xsd prefixes are implicit in PROV-N and the grammar forbids redeclaring them, so the serializer never writes those declarations; a document that binds either prefix elsewhere is handled as described under "Reserved prefixes" above. Every other prefix is checked against the PN_PREFIX production before it is written, Unicode included, so a prefix that starts with a digit or ends in a dot is refused rather than emitted as unparseable text.

PROV-JSONLD notes

PROV-O models specializationOf, alternateOf, hadMember, and mentionOf as plain object properties, and PROV-Dictionary does the same for hadDictionaryMember. A statement in one of those forms is a single triple on the subject node, with no node of its own, so there is nowhere to write a relation identifier or extra attributes. Serializing a document whose record carries either throws Prov\Exception\ProvException rather than writing the triple without them. Every other relation has a qualified form (prov:qualifiedGeneration, prov:qualifiedInsertion, ...) that carries both.

A relation is written as a property of its subject node, so a relation whose subject formal is missing has no node to hang on. One that carries an identifier, attributes, or another formal throws Prov\Exception\ProvException; one that carries nothing else states nothing and is dropped. A relation that has its subject but no object formal keeps its qualified form, which PROV-O allows without the object, so nothing is lost. The five relations above have no qualified form, so a missing object throws there too.

The whole document shares one @context. Bundle declarations are promoted into it when their prefix is free there; a bundle prefix that rebinds a document prefix cannot be, and names under it are written with a minted prefix instead, so every compact IRI expands to the URI the model carries.

Document operations

use Prov\Operation\DocumentOperations;
use Prov\Operation\DocumentComparator;

$merged = DocumentOperations::merge($docA, $docB);
$flat = DocumentOperations::flatten($docWithBundles);            // throws if Mentions present
$flat = DocumentOperations::flattenDroppingMentions($docWithBundles);

DocumentComparator::equals($a, $b);  // structural (semantic) equality

Querying a document

ProvGraph indexes a document (or bundle) once and answers edge queries by identifier, accepting QualifiedName objects, prefix:local shorthands, or full URIs:

use Prov\Operation\ProvGraph;

$graph = new ProvGraph($document);

$graph->relationsFrom('ex:article');       // relations whose subject is ex:article
$graph->relationsTo('ex:writing');         // relations whose object is ex:writing
$graph->relationsReferencing('ex:plan');   // any endpoint, including secondary ones
$graph->generationsOf('ex:article');       // Generation records of an entity
$graph->usagesOf('ex:draft');              // Usage records of an entity
$graph->recordByIdentifier('ex:article');  // O(1) record lookup
$graph->agentsOf('ex:writing');            // agents associated with an activity

ProvGraph::referencedIdentifiers($relation);  // every endpoint of one relation

agentsOf() returns one AgentInvolvement per association, each carrying the agent, the plan the association named, the association's attributes (so prov:role survives), and onBehalfOf: the chain of agents this one acted on behalf of, walked from the actedOnBehalfOf delegations (nearest responsible first, activity-scoped delegations honored, cycles guarded). It reports identifiers and structure only; read an agent's prov:type with recordByIdentifier() to classify it.

The graph covers the container's own records; flatten a document first to query across bundle boundaries. For type-centric queries (all Usage records), Document::getRecordsByType() remains the right tool.

Scanning stored PROV-JSON

JsonScanner answers slice queries straight off decoded PROV-JSON, without building the Document object graph, for the case where a stored document is large and a read wants a few facts from it. Identifiers and attribute names match by URI, so the prefix a document spelled them with does not matter:

use Prov\Scan\JsonScanner;

$scanner = new JsonScanner($json);

$scanner->ids('entity');                                            // record ids of a section
$scanner->attributeValue('entity', 'ex:article', 'dct:title');      // first value, as decoded
$scanner->stringValue('activity', 'ex:writing', 'ex:note');         // ?string
$scanner->intValue('activity', 'ex:writing', 'ex:exit_code');       // ?int
$scanner->dateTimeValue('activity', 'ex:writing', 'prov:startTime'); // ?DateTimeImmutable
$scanner->attributeBag('agent', 'ex:alice');                        // Attributes, as on the deserialized record
$scanner->relations('used');                                        // ScannedRelation list: endpoints + attributes
$scanner->relationAttributeBag($relation);                          // a relation's annotations as Attributes
$scanner->relationsReferencing('ex:article');                       // every relation naming an identifier
$scanner->agentsOf('ex:writing');                                   // agents, with their delegation chains

attributeValue() returns the value as decoded, so a dateTime, a language-tagged literal or a qualified-name reference comes back as its raw typed map; the typed reads and the bags apply the deserializer's mapping instead. Record-level damage is skipped, structural damage throws at construction. The scanner reads the top-level document only; deserialize to work across bundles.

Validation

$result = Prov::validate($document);

if (!$result->isValid) {
    foreach ($result->violations as $violation) {
        echo "[C{$violation->constraintId}] {$violation->message}\n";
    }
}

// Or throw if the document has any violations:
Prov::validate($document)->throwIfInvalid();  // raises ConstraintViolationException

Coverage is partial: rules that need transitive graph reasoning over derivation chains aren't implemented, so $isValid === true only means no checked rule was violated. Use ConstraintValidator::implementedConstraints() or ::unsupportedConstraints() to see the exact set.

Builder tips

Namespaces. Register namespaces one at a time (namespace(), addNamespace()) or in bulk from an application-wide registry (addNamespaces($iterable)); DocumentBuilder also accepts an iterable to preload at construction. Re-registering a prefix with a different URI throws, including the prov/xsd built-ins, so a typo cannot silently corrupt a binding. build() prunes the declarations down to the namespaces your records actually reference, so registering many namespaces up front does not bloat the serialized output; call keepUnusedNamespaces() to keep them all. Documents obtained from Prov::deserialize() are not affected: they keep every namespace they declared.

Attributes. Pass attributes as an associative array: keys are resolved as namespace shorthands, and a list value adds one entry per element (that is how a repeated key is written, since PHP array keys are unique):

$builder->entity('ex:e1', [
    'prov:label' => 'My entity',
    'prov:atLocation' => ['ex:rack1', 'ex:rack2'],  // two prov:atLocation values
]);

String values stay string literals, with one exception: a prov:type value written as a registered shorthand ('prov:type' => 'ex:Document') resolves to a qualified name, because prov:type values name types rather than carry text. For every other key, a string like 'workspace:stage' is stored verbatim; pass a QualifiedName object when you mean a reference. Prov\Attribute\AttributesBuilder offers the same rules imperatively, useful when attributes accumulate across code paths:

$attrs = new AttributesBuilder($namespaceManager)
    ->add('prov:type', 'ex:Document')
    ->addAll('prov:atLocation', $locations)
    ->build();

Two Attributes bags combine with $a->merge($b): a multimap union that keeps all values under a shared key (the way to promote a single value to several).

Blank nodes (anonymous records):

$e = $builder->blank();          // _:b1, auto-minted
$builder->entity($e);
$builder->wasGeneratedBy(entity: $e, activity: 'ex:writing');

Use QualifiedName::blankNode('b1') instead when you control the label.

Bundles. withBundle() is the recommended form: it builds the bundle eagerly, inline, without breaking the fluent chain:

$builder
    ->entity('ex:e1')
    ->withBundle('ex:b1', fn ($b) => $b
        ->entity('ex:e2')
        ->wasGeneratedBy(entity: 'ex:e2', activity: 'ex:a1'))
    ->build();

Two alternatives exist for other flows: bundle() returns a detached BundleBuilder that you drive directly and that is built lazily when the document's build() runs, and addBundle() attaches an already-built Bundle (for example one obtained by deserializing).

DocumentBuilder::build() and BundleBuilder::build() are single-use; a second call throws LogicException.

Learn more

Every public class carries an inline docblock explaining what it's for. The most useful starting points:

• Prov\Prov: the facade used in the examples above
• Prov\Builder\DocumentBuilder: the full set of record and relation methods
• Prov\Format: supported serialization formats
• Prov\Constraint\ConstraintValidator: what each PROV-CONSTRAINTS rule checks

Development

Before submitting a PR, run composer check (format, lint, analyze, tests).

See also

• trungdong/prov: Python implementation of PROV-DM.
• lucmoreau/ProvToolbox: Java toolkit for PROV.

License

This library is made available under the MIT License. Please see LICENSE for more information.